The invention relates to improvements in dosing of a powder from a canister, in particular, for the use in foodservice dispensing equipment. The canister of the invention may, for example, be used to dispense in a more consistent manner metered quantities of dry powdered food material having poor intrinsic flowing properties.
Various automated beverages or food dispensers for making hot or cold reconstituted products are known in the art. In a conventional beverage or food dispenser, a metered amount of water-soluble beverage-forming or food-forming powder supplied from a storage canister, and a complementary metered amount of hot or cold water supplied from a water source are mixed to produce a final product, which is dispensed into a cup or glass.
Cohesive and hygroscopic powders, such as milk powders, gravy and the like and containing fat and/or humectant ingredients, are difficult to dispense out of a beverage or food canister in a consistent manner and are difficult to fully evacuate from the canister. In particular, cohesive powders do not flow well due to compaction and/or decompaction of the powder, lumping, cliffing and bridging inside the canister.
There are mainly two identified issues with dispensing these powders in the traditional canisters.
The first issue relates to the consistency of powder dosing that more particularly refers to the dose-to-dose variation. Typically, the gram-throw of powder dramatically decreases after a certain number of throws and the reconstituted beverage or food becomes more diluted. In terms of product quality, the consistency of the product is important for meeting the satisfaction of the consumer. If the dose-to-dose variation is too large, e.g., on the order of 5% of powder discrepancy or more, it effects the in-cup quality of the product in a way that becomes perceptible for the consumer.
The second issue relates to the powder evacuation out of the canister which may be incomplete or consistent within a predetermined tolerance. In short, the canister is unable to empty up to a certain point and a significant amount of powder remains. In traditional canisters, powder evacuation includes doses or gram-throws that are below the target throw as well as powder that remains in the canister after the dosing mechanism cannot further deliver powder. In terms of autonomy, low powder evacuation requires the canister to be more frequently filled by the operator, in order for the beverage not to become unacceptably weak when the powder level becomes low. Therefore, such low performing canisters may impact product quality and may require more attention from the operator in re-filling and maintenance of the device.
Current systems typically consist of a single rotary wheel and a breaking mechanism such as wire tapers or springs attached to the wheel. Typical canisters are described in U.S. Pat. Nos. 3,013,701 and 4,207,995.
Dosing is usually performed by an auger, either a spring or screw auger. The dosing end of the canister contains an exit that directs the powder towards the mixing area as it exits. These systems are effective when the powders to be dosed have moderate to good flow properties, but this effectiveness decreases when a poor-flowing, cohesive powder is used.
Therefore, there is a need for an improved dispensing canister that provides a better powder dosing consistency and a more complete and reliable powder evacuation than the known canisters of the art, in particular, when using moderate or bad flowing powders. The present invention now provides such a canister.
The dispensing canister of the invention comprises a reservoir having two terminal walls, a rotatable volumetric dosing means longitudinally extending in the reservoir between the terminal walls, a main agitating wheel operatively associated with the rotatable volumetric dosing means to rotate in the reservoir upon actuation of the rotatable volumetric dosing means, and a secondary agitating wheel operatively associated with the main agitating wheel, wherein the wheels are vertically offset so that the main wheel is positioned closer to one terminal wall and is arranged to act in a downward rotation closer to that wall with the secondary wheel being positioned closer to the other terminal wall and being arranged to act in a downward rotation closer to that wall.
The reservoir generally includes two side walls, while the terminal walls includes a front wall and a rear wall. Usually, the dosing means is arranged in the bottom of the reservoir between the two terminal walls. A main agitating wheel is arranged to gear on the rotatable volumetric dosing means so as to rotate in the reservoir upon actuation of the rotatable dosing means. The invention is mainly based on the principle that a secondary agitating wheel is arranged to gear on the main agitating wheel. More preferably, the main agitating wheel is arranged to act in a downward rotation closer to a first terminal wall whereas the secondary wheel is arranged to act in a downward rotation closer to the second terminal wall. Therefore, the two wheels are vertically offset one another and are arranged in rotation in such a manner that they promote a downward pushing effect of the powder along the terminal walls. As a result, the powdered material tends to become loosened along the terminal walls of the canister and powder structures are unable to settle in these areas.
In a preferred embodiment, the rotatable volumetric dosing means is a screw auger or, alternatively, a spring auger and the auger is arranged to transport a volume of powder that varies as a function of the longitudinal position along the dosing means. It has been surprisingly found that remarkable results on dosing consistency and evacuation could be successfully obtained if the auger had a variable volumetric configuration used in combination with the aforementioned two-wheel offset configuration that promotes the downward pushing effect along the walls.
In a possible embodiment, the auger may be arranged to comprise a volume of transport for the powder that is greater in the rear portion of the auger than in the front portion of the auger. For that, the auger may be an helicoidal spring auger with a solid insert placed within the spring in a front part of the auger. A solid insert reduces the volume available for moving the powder forward in the front region of the canister whereas more powder is moved from the rear region of the canister. As the volume reduces in the front, the powder tends to compact in a lower available volume near the outlet thereby maintaining the powder density and minimizing the dosing variations.
In another embodiment, the auger may be arranged to comprise a volume of transport that is greater in the front portion of the auger than in the rear portion of the auger. For that, the auger may be an helicoidal spring auger with a solid insert placed within the spring in rear part of the auger, thus reducing the capacity of the auger to move the powder in the rear region as opposed to the front region of the canister and thereby reducing cliffing at the front terminal end.
The invention also relates to a method for dispensing a beverage-forming or food-forming powder from a dispensing device having a reservoir and a rotatable volumetric dosing means longitudinally extending in the reservoir between terminal walls. The method comprises providing agitation on the terminal walls of the reservoir when the dosing means is rotated so as to enhance gram throw performance or dosing time of the dispensing device. By this method, dosing time can be increased by at least 20 to 40% or the number of throws can be increased by at least about 50 to 66%.